class: center, middle, inverse, title-slide # To PEEP or not? and how to… ## ⚔<br />Journal Club ### Teddy Tun Win HLA, ST5 Intensive Care Medicine ### AICU Chelsea and Westminster Hospital ### 2021/12/01 (updated: 2021-12-01) --- # PLAN <br> <br> - Brief background - Rationale behind studies - Discussion - Summary <br> -- <br> - Estimated time : **45 mins.** --- # Acute Respiratory Distress Syndrome - made up disease for intensivisits. :) - First described in 1967. - first consensus defintion in 1994 - heterogeneous - final consensus called **the Berlin Definition** in 2012! -- ### Definition ¹ - within 1 week of known insult : **Acute** - Bilateral opacities not explained by effusions, collapse - non cardiogenic oedema or fludi overload - Hypoxemia quantified by PaO2/FiO2 ratio : **Respiratory Distress** - Histology² = "presence of alveolar oedema with injury of pneumocytes and vascular endothelium essentially _non-specific_ **Syndrome** .footnote[ [1] Acute Respiratory Distress Syndrome BJA [link](https://academic.oup.com/bjaed/article/17/5/161/3782744) [2] Histology of ARDS [link](https://www.pathologyoutlines.com/topic/lungnontumordiffusealveolardamage.html) ] --- class: left # Does ARDS matter? ### Epidemiology - Incidence in the UK - highly variable - 2.5% to 19% of ICU patients¹ -- .pull-left[ ### Morbiditiy and Mortality ¹ - Fewer Ventilator-free days - median 27 days - Longer ICU stay - median 15 days vs 3 - ICU mortality of **41.9% vs. 11%** in non-ARDS ventilated patients. - ARDS +/- **RV Dysfunction** = odds ratio 1.45 ² ] -- .pull-right[ ### Causes - **Direct Lung Injury** : Pneumonia(69%), Aspiration, Pulmonary Contusion, Drowning, Inhalational Injury - **Indirect Lung Injury** : Sepsis, Severe trauma, Pancreatitis, Anything causing "cytokine storm" ] .footnote[ [1] Incidence ARDS in Thorax [link](https://thorax.bmj.com/content/thoraxjnl/71/11/1050.full.pdf) [2] RV Failure [link](https://ccforum.biomedcentral.com/articles/10.1186/s13054-021-03591-9) ] --- # Management of ARDS - no curative option - only best supportive care - concept of baby lung - Gattinoni et al late 90's - permissive hypercapnia - Hickling et al -- .pull-left[ ### ARMA trial(2000) - low versus high tidal volume trial - 6ml/kg PBW & Pplat < 30cm vs. 12ml/kg PBW & Pplat< 50cm - Mortality improvement : 31.0 vs. 39.8% ] -- .pull-right[  ] -- ### Guideline on Management of ARDS (2019) - FICM, ICS, BTS Consensus over **6 years** .footnote[ [1] ARMA [link](https://www.nejm.org/doi/full/10.1056/nejm200005043421801) ] --- # 2019 ARDS guideline and ...  - higher PEEP : what is a high PEEP? -- - ALVEOLI 14.7, LOV 105 15.6, ExPRESS 14.6 -- - **HOW** to set PEEP? --- background-image:url("PEEPeffects1.png") background-size: contain --- # Consequences of PEEP ¹ -- .pull-left[ ### Beneficial Effects - counteract alveolar collapse - reduce intrapulmonary shunt - mitigate VILI by reducing cyclical opening and closing. - promote homgeneity of lung ] -- .pull-right[ ### Harmful Effects - reduce cardiac output - increase pleural pressure, right atrial pressure - increase pulmonary vascular resistance - increase alveolar deadspace ] -- ### At Bedside - Default approach : PEEP table -- - Pressure approach : Driving Pressure, Pressure-Volume Curves and Stress Index -- - Imaging : CT, Lung Ultrasound, Electrical impedance tomography -- - Respiratory Mechanics : **Estimating transpulmonary Pressure** <br> .footnote[ [1] Sahetya(2017) _Setting PEEP in ARDS_ ] --- #Oesophageal ballon .pull-left[  ] .pull-right[  ] -- - take into account chest wall compliance (kyphoscoliosis, obesity, ascites) - NB: ?does left lower lobe Ppleural reflects overall lung Ppleural ? --- # Realworld evidence? -- ### EPVent Trial (NEJM 2008) - Population : single-centre, mixed medical surgical ICU -- - Intervention : heavy sedation +/- paralysis, Recruitment manouvre 40cmH₂O for 30 seconds, TV 6ml/kg PBW - PEEP set to achieve P_L at 0-10cm of water at End-expiration -- - Control Group : TV 6ml/kg, recruited, FiO2/PEEP table -- - Outcome : groups well matched, median APACHE score 26.3, PaO2/FiO2 ratio, Compliance - comparable between groups.  --- #EPVENT2 (JAMA 2019) - _same question as before but **bigger** and **longer(5+1 years)**_ -- - Population : multi-centre, randomised-controlled trial, 14 sites in N America. - Intervention : PEEP titration based on Poesophagus (n = 102) vs. Control (n = 100), APACHE score mean 27 vs 28.  --- background-image:url("06.png") background-size: contain --- # EPVent2 Reanalysis (2021) -- - adjusting for disease severity (APACHE II score) -- - accounting for heterogeneity of treatment effect -- - APACHE score evenly distributed and normal in both control v treatment arms -- .pull-left[  ] .pull-right[  ] <br> - Ventilator free days and shock free days mirror mortality. --- background-image:url("09.png") background-size: contain --- # Discussion - **Complexity Bias** -- - Do we as specialists prefer complex things because it validates our own raison d'etre? -- - low APACHE score - i.e., primary single organ ARDS patients - may benefit from careful titration of PEEP using Oesophageal ballon as mortality probably from lung injury. -- - High APACHE score - i.e., multi organ sick patients - probably careful lung titration does not outweigh cause of death from non-pulmonary causes. e.g,. haemodnyamics. -- - What does it mean for **COVID** patients - usually predominant single organ? -- ## SUMMARY - Simple things work : Lung Protective Ventilation (TV 6 to 8ml/kg PBW), NMB, Prone - But there is a role for complex things. --- class: center, middle ## Questions ? -- ## Thank you ! :) --- class: center, middle # Thanks! Slides created via the R package [**xaringan**](https://github.com/yihui/xaringan).